1. Field of the Invention
This invention relates to an extruder screw for use in an extruder for molding foamed plastic articles.
2. Discussions of the Prior Art
When molding foamed, microcellular plastic articles it is important to produce uniform cell sizes. Both durability and strength of the molded articles are dependent upon cell size and uniformity. In the extrusion molding of foamed articles, the usual manner of controlling cell size and uniformity include altering the foaming agent, pressure and temperature of extrusion, and changes to the mixing portion of the extruder. In spite of the various efforts, a need still exists for foamed plastic articles containing pores or cells of uniform size and distribution.
The object of the present invention is to meet the above defined need by providing a relatively simple extruder screw for use in the molding of foamed plastic articles of uniform cell size.